And next tonight, we'll show you that astonishing video of a woman falling overboard from a cruise ship, adrift at sea for 90 minutes before her rescue, is there anything that could have protected her? Abc's reena ninan on what she herself learned when she took a plunge. Reporter: It was a dream vacation aboard a cruise ship, but this is sarah kirby after a night of heavy drinking. Everybody was drinking to excess and I was enjoying it. With everybody on the cruise and honest -- Reporter: You got pretty drunk last night. Yes, ma'am. Reporter: In this surveillance video she's falling after going to a balcony for fresh air. The next thing I knew I was falling and I panicked, pure terror. Reporter: Her friends immediately alerted the ship's staff. They searched, reviewed the video and then turned back. Still sarah was floating in the dark water for an hour and a half before being rescued. A terrifying ordeal. But, a lawyer for the cruise industry says this sort of fall is incredibly rare. He says only 1 in 1.6 million passengers goes overboard. You don't get blown or swept off a cruise ship. It does not happen. All of these incidents unfortunately are accompanied by some reckless, deliberate act. Reporter: But, we wondered, is there a technology that could have alerted the ship sooner? Some companies say yes. So, we checked it out. I suited up and then jumped overboard off this small boat. An alarm is triggered by a laser while a computer pinpoints my exact location. The industry says the technology is just not there yet. There are a lot of false positives, false negatives. These systems work great on land, but they're still being adopted for use at sea. Reporter: There are a number of alarm systems out there, but very few ships have them. Our parent company, disney, told us they have overboard technology on their ships. As for sarah, she says being anywhere near the water is now just too painful, a reminder of that terrifying night. Reena ninan, abc news, miami.

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